about his older brother who was shot by police, did he have radical ties overseas? Abc's brian ross with that. Reporter: Federal authorities today were searching behind a cambridge drug s area where the brother's father used to repair cars, looking for more possible explosives or where the bombs are made. So far, there's no evidence of a continuing threat. The fbi also wants to question tamerlan's wife, seen over the weekend, leaving the family apartment. A rhode isla native, she converted to islam and changed her name. Because she lived in the same the two brothers hatched their plot, she could provide clues about whether others were inlved. Her family issued a statement today saying, we know that we never really knew tamerlan tsarnaev. Local prosecutors said they're investigating whether tamerlan was involved in the brutal murder of three young men, one of whom was his roommate. The three were found with their throat slashed, covered in marijuana and cash. Also under investigation, the six-month trip he took to russia, at a time that rebel groups there carried out a number of violent attacks. As abc kirit radia discovered in the dagestan region. Last year alone, dagestan lost 115 police officers in nearly 300 terror attacks. This street was obliterated by a car bomb. Caller: Investigators say they want to know whether tamerlan met with leaders there. Neighbors say tamerlan was a changed man when he returned to the u.S., Off tobacco, and alcohol, linking to extremity jihadist videos and saying, I don't have any american friends. I don't understand them. A neighbor said he expressed anger about america and christianity. He said the bible is a cheap copy of the koran, that most american wars are excused with the bible. Reporter: Today the mother of the boys told abc news, that tamerlan was always the leader of her two boys. And that after the bombing, he called her to say, everything is okay, thanks to allah. There continue to be questions about that six-month trip to russia. The fbi had interviewed tamerlan before he went, at the request of russia, who thought he was a possible terrorist. But the fbi did not become aware he made the trip, apparently because his name was misspelled on the flight manifest. So there was no follow-up by the fbi, diane. It was a misspelling. I hear you have late word on possible ties overseas? Reporter: The continuing information coming from the hospital b and the interview there, koor r. According to sources talking to abc news, is that there's no direct tie from any overseas operation. This is primarily a self-radicalization, they learned all they knew from the internet. All right, brian ross, thanks to you and the whole team. And now we will move on to

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